Light-sensitive diazotype material



United States Patent Ofi 2,773,768 Patented Dec. 11, 1956 LIGHT-SENSITIVE DIAZOTYPE MATERIAL Theodorus Petrus Wilhelmus Sanders, Venlo, and

Johannes Henricus Andreas Wilders, Blerick, Netherlands, assignors, by mesne assignments, to Chemische Fabriek L. van der Grinten N. V., Venlo, Netherlands, a corporation of the Netherlands No Drawing. Application March 11, 1952, Serial No. 27 6,062

Claims priority, application Netherlands March 20, 1951 19 Claims. (Cl. 9675) The invention relates to lightsensitivc diazotypc material and particularly to diazotype material comprising a support bearing a diazo film layer of the so-called one-component type which is suitable for development with a thin layer of an aqueous developer. By material of the one-component type is meant the type in which the diazo film layer contains a diazo component but no coupling component.

By the term diazo-film layer" as used herein is meant a special type of diazo layer. The generic term diazo layer" is also used when the diazo compound is simply spread out on the fibres of a paper surface as a dried-up coating, perhaps in the form of a very thin. uneven, and possibly discontinuous diazo surface. A diazo film layer in accordance with the present invention has the character of a true layer of measurable thickness. A diazo film layer need not be of uniform thickness through out; it may for example, show a relief. Such a diazo film layer comprises material which will be referred to hereinafter as film-forming material."

The demarcation between the support and the diazo film layer may be sharp, as is generally the case with a layer cast on to a support. A sharp demarcation may, however, be absent, as is the case, for example, when a cellulose ester film is superficially saponified and the diazo compound is absorbed into the saponified surface. in this case the unsaponified part is considered as the support and the saponified part constitutes the film layer; the acyl content of the latter increases from the outside to the inside. In this case also, the diazo film layers are clearly distinguished from diazo layers of the type described above even though there be no sharp demarcation between the diazo film layer and the support.

Light-sensitive diazotype materials with a diazo film layer are known. Mention may be made of cellulose acetate films with a deacylated surface, impregnated with a diazo compound without any azo coupling component, and of the diazo film layers with an 2120 coupling component described in British specification No. 563,804. Diazolype material containing a diazo film layer including an azo coupling component. the film-forming material of which consists of gclatine, has also been produced. Photographic material with a lighbsensitive layer of cellulose acetate with a low acetyl content has been described in British specification No. 496,049. This specification chiefly relates to material in which the light-sensitive substance is a silver halide, but reference is also made to colouring processes based on the use of diazo compounds without any further information being given. Other types of diazo film layers are described in British specifications Nos. 311,196, 318,511 and 563,547.

The known diazotype materials with a diazo film layer or the one-component type, are developed by the application of a thin layer of aqueous developing liquid. The developer usually contains phloroglucinol, a very active coupling compound, which may couple with the diazo compound in one. two or three positions and produce dyes in various shades accordingly. Use may also be made of a mixture of phloroglucinol with other coupling components, for example rciorcinol, with a view to producing good neutral shades.

The diazo film layers need to be resistant to treatment with the thin layer of aqueous developer, i. e. the filmforming material employed must not present any serious difificulty when treated with an aqeous liquid. for example by reason of melting, dissolving, or becoming objuc tionably sticky, as is the case with layers of. gum, alkyl cellulose, soft gelatine and similar substances. On the other hand it must be capable of readily accepting and absorbing the thin layer of developer.

Suitable film layers are, for example, cellulose (cellulose hydrate of cellophane) films and the like, and in particular layers of cellulose esters of such an acyl content that they can absorb the aqueous developer. Other suitable layers are those of polyvinyl esters with such an acyl content. Such layers can very readily be obtained by deacylation of layers with a higher ucyl content. in the case of the cellulose ester layers tleacylation may be very extensive or even complete.

When diazo film layers of a material suitable for thin layer treatment with an aqueous developer are employed, the difficulty is experienced that they are more sensitive than ordinary diazotype papers to so-czilled developing iuctuations when polyvalent azo-dyestulf components are applied. Usually these fluctuations arise because the quantity of the developer applied is not entirely constant. for example owing to jerks or vibrations of the developing equipment or variations in its speed. Vuriulion in the concentration of the developers, for example owing to an error in the preparation of the solution or its evaporation during use also lead to fluctuations and so do slight irregularities in the manufacture of the diazo film layer, as a result of which the latter does not absorb the developer perfectly uniformly. Developing fluctuations are more frequent with modern equipment than they were formerly; in earlier apparatus a large excess of diluted developer was used while now the aim is to keep as small as possible the quantity of the developer applied per unit of surface area. In order to yield strong copies the diazo film layers must contain large quantities of the diazo compounds per unit of surface area. If this quantity is expressed in millimols of diazo compound per sq. metre. it may be stated that the ordinary diazotype papers contain about 0.3 to 0.5, and the modern diaaotypc material with diazo film layers generally more (sometimes up to 1.0 and even 1.5 millimols) diazo compound per sq. metre. These diazo film layers are particularly sensitive to developing fluctuations.

The sensitivity of diazo film layers to developing Eluctuutions shews itself in variations of the shades in the colours of the image, for example in deviations from the desired neutral black. Jerks and vibrations in the developing equipment are thus noticeable in the copies, particularly if large dark areas are present in the image, as streaks with alternate shades of, for example, green-black and violet-black.

According to the present invention. lightseusitivc d1 axoiype material containing a support bearing a diazo tiim layer of the so-called one component type which is suitable for development with a {hill layer of a developer contains in the diazo film layer a diazo compound of the general formula:

in which X is an anion and R1 and R2 are alkyl radicals having together 10. ll or 12 carbon atoms. each nlkyl radical containing at least four and at most seven carbon atoms. and not more than one of the two having a side chain attached to the alpha carbon atom.

Even when the diazo content is high and development takes place with a thin layer of a developer containing polyvalent azo components such as phloroglucinol and resorcinol, light-sensitive diazotype materials of this composition are less sensitive to developing fluctuations than those containing in the diazo film layer other diazo com pounds that are suitable per se for such development, for example the well-known, frequently applied, and otherwise eminently suitable paradiazo-ethyl-benzyl-aniline.

The light-sensitive diazo film layers according to the invention may contain the admixture generally used in diazotype printing, such as acids, stabilisers, anti-disco]- ouration agents, and the like. The diazo film layer may be cast on to the support, the casting material already containing the diazo compound. In employing the casting process. however it is preferable to cast the film layer. allow it to set and dry, and then impregnate it with a solution of the diazo compound. It is also possible to cast the film layer on to another support, for example a cylinder surface, and transfer it after drying to the desired support, again with the diazo compound already present in the casting material or with subsequent impregnation.

Film-forming material mainly consisting of hydrolysed cellulose acetate with an average acetyl content, ex pressed as combined acetic acid, of by weight to 35% by weight is particularly suitable for diazo film layers With the above types of diazo compounds. This corresponds to an average number of acyl groups attached to the OH groups of 0 to about 1.4 (triacetate:=3.0). Such film layers can be obtained in the manner described above by casting, with or without a subsequent impregnation, but also by partial deacylation of the surface of a foil or film of cellulose acetate with a higher acetyl content. In the latter case the acetyl content in the film layer formed is not the same throughout; in a cross-see lion through the support with the film layer it will stead ily increase from the outside of the said layer inwards. The basis taken is the average found in the part of the film layer that does not dissolve in dry acetone.

It has been found advantageous to have the film layer mounted on a hydrophobic sublayer. This may be formed separately. With superficially deacylated cellulose acetate layers it will already be present, since the original cellulose acetate is hydrophobic owing to its high acetyl content. The cellulose acetates may also contain other acyl radicals besides the acetyl radical.

As diazo compound that in which R1 and R2 are both normal-hexyl radicals is particularly suitable.

Suitable supports for the diazo film layer are, for ex ample, paper, baryta-coated paper, transparent paper, linen, Celluloid film, cellulose acetate film, plastic supports, metal sheets and glass.

It the materials according to the invention are propcrly made, they can be used for making copies w ich have to meet high demands as to the strength of the image and the uniformity of shade, for example for copying originals of artistic value, photographic diapositives, cinematographic films, and the like.

The following examples will serve to illustrate the invention but are not to be regarded as limiting it in any way.

Example I Paper of weight 150 g. per sq. metre, coated on one side with a cellulose acetate (about 50% by weight of combined acetic acid) layer of about my. thickness. which has been applied on the paper by means of an adhesive and which is deacylated to a depth of about 4 me to an average acetyl content. calculated as combined acetic acid, of about by weight (which corresponds to an average number of acetyl groups attached to the OH groups of 0.7) is sensitized by impregnation for seconds on the deacetylated side of the cellulose acetate layer with the following solution:

Zinc chloride double salt of p-diazo-di-n-amylaniline g 20 'i'artaric acid g l Ammonium chloride g 2 Ethyl alcohol (96%) -cc I00 Vater -cc 900 he excess liquid is removed from the cellulose acetate surface, and the material is then dried. it then contains about 0.36 g. of the diazo compound per sq. metre, which corresponds to about 1 millimol. per sq. metre. The diazo film layer formed is thus located on a hydrophobic tcllulosc acetate layer having the original acetyl content and having a thickness of about 6 ma.

After exposure under a diapositive the material is dcveloped by the application of about 9 g. per sq. metre of a developer having the following composition:

Thiourea "g- 30 Phlorogluciriol g 6.5 Resorcinol g 6.5 Potassium hydroquinone monosulphonate g 1 Sodium isopropylnaphthalenesulphonate g 3 Mannitol g 25 Potassium-tetraborate-pentahydratc g Potash ..g 10 Water cc 1000 a good strong black image is obtained. When the concentration of the components of this developer has increased, for example owing to evaporation of water from the developer in the developing equipment, to such an extent that the original volume of about 1050 cc. has t|C- creased to about 800 cc., and a copy is developed on this light-sensitive material by an identical procedure using this more concentrated developer, the shades of the medium tones do not dificr substantially from those of the image obtained with a. developer of normal concentration.

When, instead of 20 parts of p-diazo-dim-amylanilinc- ZnClz salt, 19 parts of p-diazo-ethylbenzylaniline-ZnClz salt is used for the sensitising of the film layer, the developer of normal concentration yields a good dark shade in the medium tones, whereas the developer concentrated to 800 cc. yields a brownish shade.

Example I] A paper with a film layer as described in llxample l is sensitised in the same way with a solution of:

Zinc chloride double salt of p-diazo-sec. amyl-nhexylaniline g- 23 Citric acid g 2 Ammonium chloride g s 2 Ethyl alcohol (96%) cc l00 Water cc 900 It then contains about 0.4 g. of diazo compound per sq. metre which corresponds to about 1.0 millimol of diazo compound per sq. metre. The diazo film layer thus formed is located on a hydrophobic sublayer, as in Example 1.

After exposure under a tracing with insufiicient ligh for complete exposure, the material is developed in a developing equipment of the kind described in British P. S. 656,674 at a rate of 5 metres per minute, 8.5 g. per sq. metre of the developer according to Example I being applied at normal strength. A strong black image on a good grey background is obtained.

If the rate of development in the above developing equipment is reduced to 2 metres per minute, the application of the developer is reduced to about 7 g. per sq. metre. The image then obtained however is practically identical with that obtained at a rate of development of 5 metres per minute.

Example III A paper with a film layer as described in Example I is sensitised in the same manner with a solution of:

Zinc chloride double salt of p-diazo-di-isoamylaniline g 24 Alum g l Di-ammonium citrate g 4 Ethyl alcohol (96%) cc 200 Water cc 800 It then contains about 0.45 g. of diazo compound per sq. metre, which corresponds to about 1.2 millimols per sq. metre. As in Example I, the diazo film layer described above is located on a hydrophobic sublayer.

After exposure under a diapositive, the material is developed at a rate of 1.50 metres per minute, 7 g. per sq. metre of the developer according to Example I being applied.

A strong black image is obtained in which, even when large areas of medium tone are present, few if any deviations in shade resulting from vibrations and mechanical inequalities of the developing. equipment are to be noticed. When instead of 24 parts of p-diazo-di-isoarnylaniline-ZnClz salt, 23 parts of p-diazo-ethyl-benzylaniline- ZnCLz salt are employed, large areas of medium tone in the image shew, as a result of inequalities in the developing equipment, variously coloured streaks.

Example IV A cellulose acetobutyrate film of 100 mu thickness with an average a-cyl content of 31% by weight of acetyl and 17% by weight of butyryl is superficially hydrolysed on one side by dipping in a solution of: 0.35 nKOH in methylalcohol (50%) for seconds at C.

After washing and drying, the film is treated with a solution consisting of:

Zinc chloride double salt of p-diazo-di-n-hexylaniline g 22 Ammonium chloride g 5 Tartaric acid g 8 Ethyl alcohol (96%) cc 100 Water cc 900 The excess liquid is removed from the cellulose ester surface, and the material is then dried. The diazo film layer then contains about 0.8 millimol of diazo compound per sq. metre, and is located on a hydrophobic sublayer. After exposure under a diapositive with continuous medium tones, the material is developed with a phloroglucinol-resorcinol developer according to Example I, about 9 g. per sq. metre being applied. A black image with uniform shade in all the areas is obtained. Copies of this type are very suitable for projection purposes.

Example V On paper coated with a hydrophobic layer of cellulose acetate (with an acetyl content, calculated as combined acetic acid, of about 53% by weight of acetic acid) of a thickness of about 10 m a layer of 90 g. per sq. metre of the following liquid is applied by dipping at 20 C.

Zinc chloride double salt of p-diazo-di-n-hexylaniline g 10 Tartaric acid g 3 Polyvinyl acetate (about 77% saponified; a 4% by weight solution of this product in water has at 20 C. a viscosity of 31 centipoises, determined with the Hoeppler viscosimeter) g 150 Saponin g 0.25 Ethyl alcohol (96%) cc 750 Water cc 2250 The diazo film layer formed then contains about 0.9 millimol of diazo compound per sq. metre, and it is located on the hydrophobic cellulose acetate layer.

When this paper is exposed under a diapositive, the print shows little variation in shade due to developing fluctuations, even in the medium tones. When, instead of the said diazo compound, and equivalent amount of zinc chloride double salt of p-diazo-ethyibenzylaniline is used for the sensitising, so that the diazo content is similarly 0.9 millimol per sq. metre, the print obtained after exposure under a diapositive gives a clearly visible variation of the shade of the azo dyestuif with slight developing fluctuations.

Example VI A cellulose film (cellulose hydrate foil, cellophane) with a thickness of 25 m is applied on paper by means of adhesive. The film is then sensitised with the following solution:

Zinc chloride double salt of p diazo n amyl n hexylaniline g 23 Citric acid g 5 Ethyl alcohol cc 500 Water cc 500 The diazo film layer then contains about 0.4 g. of diazo compound per sq. metre, which corresponds to about 0.8 millimol per sq. metre.

After exposure under a transparent original, the mate rial is developed by the application of about 9 g. per sq. metre of the developing solution described in Example l. A strong black image is obtained, which shows little variation in shade as a result of developing fluctuations.

What we claim is:

l. Light-sensitive diazotype material comprising a support bearing a one-component diazo film layer which is suitable for development with a thin layer of an aqueous developer, wherein the diazo lm layer is a continuous substantially dry and non-sticky layer of measurable thickness that covers said support, contains an organic colloidal solid film-forming material, is hydrophilic and contains substantially entirely within said layer a diazo compound of the general formula:

in which X is an anion and R1 and R2 are alkyl radicals together having a total of from 10 to 12 carbon atoms, each alkyl radical containing at least 4 and at most 7 carbon atoms, and not more than one of the two having a side chain attached to the alpha carbon atom.

2. Light-sensitive diazotype material according to claim 1, wherein the film-forming material of the diazo film layer consists essentially of hydrolysed cellulose acetate with an average acetyl content, expressed as combined acetic acid, of 0% by weight to 35% by weight.

3. Light-sensitive diazotype material according to claim 1 wherein the support is hydrophobic.

4. Light-sensitive diazotype material according to claim 1 wherein a hydrophobic interlayer is present between the support and the diazo film layer.

5. Light-sensitive diazotype material according to claim 1 which comprises a support of cellulose ester film saponified at least on the surface to at most a low acyl content and having said diazo compound absorbed in said saponified surface.

6. Light-sensitive diazotype material according to claim 5 wherein the cellulose ester film is itself carried by a paper support.

7. Light-sensitive diazotype material comprising a support bearing a one-component diazo film layer which is suitable for development with a thin layer of an aqueous developer, wherein the diazo film layer is a continuous layer of measurable thickness that covers said support, contains as a film-forming material regenerated cellulose.

is hydrophilic, and has absorbed therein a diazo compound of the general formula:

N N X R.

in which X is an anion and R1 and R2 are alkyl radicals together having a total of from 10 to 12 carbon atoms, each alkyl radical containing at least four and at most seven carbon atoms, and not more than one of the two having a side chain attached to the alpha carbon atom.

8. Light-sensitive diazotype material comprising a support bearing a one-component diazo film layer which is suitable for development with a thin layer of an aqueous developer, wherein the diazo film layer is a continuous layer of measurable thickness that covers said support, contains as a film-forming material cellulose acetobutyrate saponified to at most a low acyl content at its surface, is hydrophilic, and has absorbed therein a diazo compound of the general formula:

NOM

in which X is an anion and R1 and R2 are alkyl radicals together having a total of from 10 to 12 carbon atoms, each alkyl radical containing at least four and at most seven carbon atoms, and not more than one of the two having a side chain attached to the alpha carbon atom.

9. Light-sensitive diazotype material comprising a sup port bearing a one-component diazo film layer which is suitable for development with a thin layer of an aqueous developer, wherein the diazo film layer is a continuous layer of measurable thickness that covers said support, contains as a film-forming material polyvinyl acetate saponified to at most a low acyl content at its surface, is hydrophilic, and has absorbed therein a diazo compound of the general formula:

in which X is an anion and R1 and R2 are alkyl radicals together having a total of from 10 to 12 carbon atoms, each alkyl radical containing at least four and at most seven carbon atoms, and not more than one of the two having a side chain atached to the alpha carbon atom.

10. Light-sensitive diazotype material comprising a support bearing a one-component diazo film layer which is suitable for development with a thin layer of an aqueous developer, wherein the diazo film layer is a continuous substantially dry and non-sticky layer of measurable thickness that causes said support, contains an organic colloidal solid film forming material is hydrophilic, and contains substantially entirely within said layer a diazo compound of the general formula:

N NQX R:

in which X is an anion and R1 and R2 are each n-hexyl radicals.

ll. Light-sensitive diazotype material comprising a support bearing a one-component diazo film layer which is suitable for development with a thin layer of an aqueous developer, wherein the diazo film layer is a continuous layer of measurable thickness that covers said support consists essentially of a cellulose ester film saponified to at most a low acyl content at its surface, is hydrophilic, and has absorbed therein a salt of p-diazo-di-n-hexyl aniline.

l2. Light-sensitive diazotype material comprising a support bearing a one-component diazo film layer which is suitable for development with a thin layer of an aqueous developer, wherein the diazo film layer is a continuone substantially dry and non-sticky layer of measurable thickness that covers said support, contains an organic colloidal solid film forming material, is hydrophilic, and contains absorbed therein a diazo compound of the general formula:

in which X is an anion and R1 is a secondary amyl radical and R2 is an n-hexyl radical.

14. Light-sensitive diazotype material comprising a support bearing a one-component diazo film layer which is suitable for development with a thin layer of an aqueous developer, wherein the diazo film layer is a continuous stubstantially dry and non-sticky layer of measurable thickness that covers said support, contains an organic colloidal solid film forming material, is hydrophilic, and contains absorbed therein a diazo compound of the general formula:

in which X is an anion and R1 and R2 are each isoamyl radicals.

15. Light-sensitive diazotype material comprising a support bearing a one-component diazo film layer which is suitable for development with a thin layer of an aqueous developer, wherein the diazo film layer is a continuous substantially dry and non-sticky layer of measurable thickness that covers said support, contains an organic colloidal solid film forming material, is hydrophilic, and contains absorbed therein a diazo compound of the general formula:

in which X is an anion and R1 is an n-hexyl radical and R2 is an namyl radical.

16. Light-sensitive diazotype material comprising a support bearing a one-component diazo film layer which is suitable for development with a thin layer of an aqueous developer, wherein the diazo film layer is a continuous layer of measurable thickness that covers said support, consists essentially of a cellulose ester film saponified to at most a low acyl content at its surface, is hydrophilic, and contains absorbed therein a diazo compound of the general formula:

in which X is an anion and R1 and R: are each n-amyl radicals.

17. Light-sensitive diazotype material comprising a support bearing a one-component diazo film layer which is suitable for development with a thin layer of an aqueous developer, wherein the diazo film layer is a continuous layer of measurable thickness that covers said support, consists essentially of a cellulose ester film saponified to at most a low acyl content at its surface, is hydrophilic, and contains absorbed therein a diazo compound of the general formula:

in which X is an anion and R1 and R2 are each isoarnyl radicals.

19. A light-sensitive diazotype material comprising a support bearing a one-component diazo film layer which is suitable for development with a thin layer of an aque ous developer, wherein the diazo film layer is a continuous substantially dry and non-sticky layer of measurable thickness that covers said support, contains an organic colloidal solid film-forming material, is hydrophilic, and contains substantially entirely within said layer more than 0.5 millimol per square meter of a diazo compound of the general formula:

3 N- Nil\ R2 in which X is an anion and R1 and R2 are alkyl radicals together having a total of from 10 to 12 carbon atoms, each alkyl radical containing at least four and at most seven carbon atoms, and not more than one of the two having a side chain attached to the alpha carbon atom.

References Cited in the file of this patent UNITED STATES PATENTS 1,756,400 Schmidt et a1 Apr. 29, 1930 1,821,281 Van der Grinten Sept. 1, 1931 1,841,653 Van der Grinten et al. Jan. 19, 1932 1,967,371 Schmidt et al July 24, 1934 2,066,918 Von Poser et al. Jan. 5, 1937 2,067,690 Alink et al Jan. 12, 1937 2,209,087 Lench July 23, 1940 2,311,016 Alink et al. Feb. 16, 1943 2,336,309 Snell et al. Dec. 7, 1943 2,532,126 Slifkin Nov. 28, 1950 FOREIGN PATENTS 332,552 Great Britain July 21, 1930 337,868 Great Britain Nov. 13. 1930 425,235 Great Britain Mar. 11, 1935 

1. LIGHT-SENSITIVE DIAZOTYPE MATERIAL COMPRISING A SUPPORT BEARING A ONE-COMPONENT DIAZO FILM LAYER WHICH IS SUITABLE FOR DEVELOPMENT WITH A THIN LAYER OF AN AQUEOUS DEVELOPER, WHEREIN THE DIAZO FILM LAYER IS A CONTINUOUS SUBSTANTIALLY DRY AND NON-STICKY LAYER OF MEASURABLE THICKNESS THAT COVERS SAID SUPPORT, CONTAINS AN ORGANIC COLLOIDAL SOLID FILM-FORMING MATERIAL, IS HYDROPHILIC AND CONTAINS SUBSTANTIALLY ENTIRELY WITHIN SAID LAYER A DIZAO COMPOUND OF THE GENERAL FORMULA: 